package splitter

import (
	"bufio"
	"bytes"
	"fmt"
	"os"
	"strings"
	"sync"

	goutil "git.fireandbrimst.one/aw/goutil/misc"
)

func writeMetadata(filename string, metadata string) {
	metapath := goutil.TrimExt(filename) + ".desc"
	goutil.WriteFile(metapath, metadata)
}

func readData(scanner *bufio.Scanner) string {
	var data bytes.Buffer
	for scanner.Scan() {
		data.WriteString(scanner.Text())
		data.WriteString("\n")
	}
	return data.String()
}

func readMetadata(scanner *bufio.Scanner) string {
	var metadata bytes.Buffer
	firstLine := true
	for scanner.Scan() {
		text := scanner.Text()
		if firstLine {
			if !strings.HasPrefix(text, "---") {
				break
			}
			firstLine = false
			continue
		}
		if strings.HasPrefix(text, "---") {
			break
		} else {
			metadata.WriteString(text)
			metadata.WriteString("\n")
		}
	}
	return metadata.String()
}

func split(filename string) {
	var metadata string
	var data string
	f, err := os.Open(filename)
	if err == nil {
		defer f.Close()
		scanner := bufio.NewScanner(f)
		metadata = readMetadata(scanner)
		data = readData(scanner)
	} else {
		fmt.Fprintln(os.Stderr, err)
	}
	if len(strings.TrimSpace(metadata)) > 0 {
		writeMetadata(filename, metadata)
		os.Remove(filename) // remove hardlink before writing
		goutil.WriteFile(filename, data)
	}
}

func SplitAll(files []string) {
	var wg sync.WaitGroup
	wg.Add(len(files))
	for _, f := range files {
		go func(file string) {
			defer wg.Done()
			split(file)
		}(f)
	}
	wg.Wait()
}